Where can I find an external battery charger for my Lumia 550?

My Lumia 550 got wet, and dropped about a week later. On the same day I dropped it, I tried to charge it and the charging symbol didn't appear on my screen. So, I turned it off, and left it to charge. However, nothing happened. I got a new battery which worked for a while, but this didn't charge either. Anywhere I could find an External Charger for the battery? It's a BL-T5A, 2100mAh.